5o6 



ON INCREASE IN SIZE 



[PT. Ill 



only held for the two echinoderms studied and not for the frog, 

 thus: 



Cleavage stages Later stages 



Sphaerechinus 

 Echinus 

 Rana ... 



2-29 



2-30 

 2-23 



2-03 

 2 -08 



3-34 



Such a comparison obviously suggested interesting conclusions in 

 view of the fact that the two alecithic eggs behaved in the same way 



30' 



29 



28 



27 



26 



25 



24 



23 



22 



21 



20 



19 



]8 



o 16 



c14 



11 

 10 

 9 



7 - 



6 - 

 5 - 

 4 

 3 

 2 

 1 h 



20 40 60 80 100 



120 

 2 



150 



200 



Minutes 

 4 Hours 



Fig. 77- 



while the yolk-laden one did not. Peter's final procedure was to 

 set side by side a quotation from van't Hoff, in which chemical 

 reactions were said to be increased 2| times for each rise of tem- 

 perature by 10°, and the overall average of his own work, i.e. 2-499. 

 Nor did he fail to point out that in inorganic chemical reactions also 

 the QjyQ increased as the temperature was lowered. 



Subsequent workers found many cases in which embryonic growth 

 followed the exponential rule. Erdmann & R. Hertwig gave figures 



